This invention relates to explosive compositions and in particular to dry mix explosive compositions such as ANFO explosive compositions.
Up until this time dry mix explosive compositions have been known and used, which generally comprise a mixture of oxidiser and fuel. Initially, composite explosives based on ammonium nitrate and a fuel sensitiser were known, but thereafter there were a number of developments for example using an oxidiser with nitrate salts added (for economic reasons), and with fuel portions including other liquids such as various grades of fuel oil, alcohols, paraffin, and nitrated paraffins. Further, other additives have often been added such as molecular explosives (TNT or smokeless powder). Further, combinations of different powdered fuels have been used to replace liquid fuels.
In dry mix compositions used up until this time, it has been common to use bulking agents such as for example to increase the density and effectiveness and performance of such explosive compositions. Such bulking agents which have been used up until this time are for example sawdust, foamed polystyrene beads or particles, vermiculite, and perlite. In addition, a bulking agent has recently been developed for use with dry mix explosive compositions, wherein the bulking agent includes vegetable protein matter, this bulking agent having particular advantages over other forms of bulking agent, as described and claimed in our copending patent application. Such a vegetable protein bulking agent can for example be chopped vegetable protein matter such as for example vegetable protein matter in the form of legumes, such as nuts, nutshells, peanut shells and walnut shells. These are by way of example only however. Throughout the specification and claims these additives will be referred to as "bulking agents", being additives or bulking agents which are added to the dry mix explosive composition, although it should be appreciated that the above are examples only of bulking agents and that the invention has equal application to other bulking agents or additives.
It has been found that one problem with dry mix explosive compositions, is that the parts thereof tend to segregate, such as for example during mixing and placement prior to detonation. Given the dry mix nature of such explosive compositions, it has been found that during mixing and placement of the parts of the composition, including the mixing of bulking agent, certain parts are lost such as for example by being blown away by the wind, by spillage and the like. This affects the effectiveness of the explosive and is expensive and generally inefficient.
It is an object of this invention to go at least some way towards overcoming or minimising these problems.
It is a further object of this invention to provide an efficient dry mix explosive composition.
Other objects of this invention will become apparent from the following description.